AMSTERDAM, Nov 13 (Reuters) - Ahold Delhaize, the Dutch-Belgian operator of grocery stores in Europe and the United States, said on Tuesday it expects to double its online sales to around 7 billion euros ($8 billion) by 2021.

"In the next three years, Ahold Delhaize expects to deliver comparable sales growth and market share gains as well as a doubling of net consumer online sales", the company said ahead of its capital markets day.

The operator of U.S. supermarket chains Stop & Shop, Food Lion and Giant last week said it would raise its original 2020 online sales target of 5 billion euros, after a 21.5 percent surge in the third quarter.

The company expects to invest 2 billion euros next year in the improvement of its delivery network and in repositioning Stop & Shop, its largest U.S. brand, while cutting costs by a total of 1.8 billion euros in the coming three years.

It also forecast high single-digit growth of earnings per share in 2019, after an expected increase to 1.50-1.60 euros this year, and said it would buy back 1 billion euros in shares next year.